The GC-MS analyses of Origanum majorana L. (OME) and Origanum vulgare L. (OVE), Lamiaceae, essential oils helped identification of 39 (96.4% of the total oils) and 43 (92.9% of the total oils) components, respectively. The major constituents of OME were terpinene-4-ol (20.9%), linalool (15.7%), linalyl-acetate (13.9%), limonene (13.4%) and α-terpineol (8.57%), whereas, thymol (21.6%), carvacrol (18.8%), o-cymene (13.5%) and α-terpineol (8.57%) were the main components of OVE. In the disc diffusion and the resazurin microtitre assays, OME showed better antibacterial activity than OVE with larger zones of inhibition (16.5- 27.0 mm) and smaller MIC (40.9-1250.3 μg/mL) against the tested bacterial strains. Only OVE displayed anti-heme biocrystallization activity with an IC50 at 0.04 mg/mL. In the DPPH assay, OVE showed better radical-scavenging activity than OME (IC50=65.5 versus 89.2 μg/mL) and both OME and OVE inhibited lionleic acid oxidation. However, in the bleaching β-carotene assay, OVE exhibited better antioxidant activity than OME. In the MTT assay, OME was more cytotoxic than OVE against different cancer cell types, such as MCF-7, LNCaP and NIH-3T3, with IC50s of 70.0, 85.3 and 300.5 μg/mL, respectively. Overall, some components of OME and OVE may have antiparasitic and chemotherapeutic activity.